Pneumatic tool



Aug. 3o, 1932. J. E. RENFER 1,874,063

PNEUMATIC TOOL Filed July l, 1929 gsheetS-sheet 2 lli TORNEY Patented Aug. 30, 1932 PATENT' OFFICE JOHN E. RENFEB, OIE` CLEVELAND, OHIO, ASSIGNOR TO THE' CLEVELAND ROCK DRILL Y i COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO PNEUMATIC moor.

i appueation flied July 1", 1929.l serial No. 375,193.

This invention relates broadlyv to pneumatic tools of the percussive type and more specifically to an improved valvular mechanism therefor Which is adapted to effectuate V the reciprocative movement of the piston.

manufacture. 1

vAnother object of this invention isl to provide a yvalvular mechanism for a rock drill, or similar tool, the various'elements of Which may be vreadily separated from the machine for purposes of renewal or repair Without the arduous labor of grinding and lapping the elements cooperating. With the substituted parts. Y

Another vobject of this invention is to provide a valvular mechanism in Which the passageways for the compressed vfluid are organized with respect to the reciprocating elements Within the machine to preclude the air cushioning effect offered the piston during its power stroke.

Another object of the invention is to confstruct a light, portableappliance, durable of construction 'and free from `protuberant obstructions.

Other objects, more or less ancillary to the foregoing, and the manner in Which all the variousobj'ects are realized Will appear in the following description, which, considered in conjunction with the accompanying drawings, sets forth the preferred embodiment of the invention.

In the drawings Fig. 1 isa longitudinal sectional view of a rock'drill embodying the present invention and. illustrating the valvular organization of the drill and the mechanism for elevating the drill against the Work.

Fig. 2 is an enlarged sectional view illustrating the drill actuating valve and the piston inl its retracted position;

Fig. 3 is a similar enlarged view illustrating the actuating valve andthe'piston in its yforwardly disposed position;

4 is a transverse sectional vieW taken on a plane'- indicated by the line 4-4 in Fig; l;

Fig. 5 is a transverse sectional vievv taken on a plane indicated by the line 5-5 in Fig. 1; and v Fig. 6 is a transverse sectional vieW taken Von a plane indicated by the line 6 6 in Fig. 1.

As will be apparent from an examination of Fig. 1 the drill comprises a cylinder 10 having a piston 11 reciprocatively mounted therein and a cutting tool tappet 12 coordiinthe manner customarily employed in tools of this type. Thep'iston 11 is formedy With a head portion 13 and a shank or stem 111, the

Vcentral portion. of Which'is slightly reduced in diameter adjacent the head to accommo- 'nated with kthe piston and the cutting tool l date 'the function ofthe valvular mechanism Y as will hereinafter be more fully described.. Mounted Within Lthe bore of the cylinder 10 there is a valve chest lcomprising a tubular Abody having a fianged head 16 anda cap.17

Which is telescopically supported yWithin the bodyand axially bored to accommodate and guide the stem'lt of the piston. Adjacent the valve chest head 16 there is a housing l finember 18in Which a rotatable control valve ing instrumentalities 20. The control valve Ahousing is-formed With a recessed portion adjacent the lvalve chest 15fvvhich, in conjunction With the valve chest constitutes a compression chamber 21. The valvechest is promunication With-the compression chamber 21 through-.a plurality of .ported canals 23 in the valve chest and intercommunicating ports 24 in'the valve chest cap Y:17. The portion of the valve chest in' `vvhich the cap-17 is pilotedis counterbored-:to receive a slidevalve 25. This valve comprises a tubular `body having a flange 26f1ormedinlits outer periph- In thevalve vided with an annular-recess formed in its p l' lnner peripheral Wall,vvh1ch 1s in iuid lcornpassageways 29 which are provided to effect f the retracted positionl of the valve 25 coninner face of the piston 'the piston lin Vclearance relative to the periphery of the sonant with the retraction of the piston. rlhe cylinder 1() is provided with an exhaust port 30 which is disposed in relation to the zone of travel of the piston 11 to lie adjacent the head at the extended position thereof. in inlet passage 36 is likewise provided in the cylinder, this passageway being formed in a ribular boss' in the cylinder Vand 'extends from ports 31 and 32 in the valve chest and cap respectively to a point adjacent the outer face of the piston at the extended position thereof.

-lnoperation let it be assumed that the control valve 19 is adj ust-ed to the position illustra'ted in Fig. 1 and that the compressed fluid is being admitted into the compression chamber 21. Let it also be assumed that the piston 11 is disposed in its retracted position as illustrated in Fig. 2. In this -event it will be seen that the compressive force of fluid acting upon the rearward faces of the piston and piston stem will cause the translation of and eflectja striking blow against the tappet 12.t During this event, however, the stem ofthe piston will be withdrawn from the opening 33 in the valve chest cap Athereby subjecting the shoulder 34 of the slide valve yto the influence of the'compressed fluid within the compression chamber.

The slide valve, as most clearly shown in gs. 2 and 3, is bored to providea liberal piston stem 14. Consequently a column of the compressed fluid will flow through this opening and acting upon the shoulder 34 will tend to restrain the forward movement effort of the fluid will overcome this resistance and drive 'the slide valve against the ledge or valve seat 27. As the piston stem .moves to its extended position it will obstruct the annular vein 22 and check the flow of compressed fluid into the cylinder, the inertia however, of the piston will carry it forward tothe position illustrated in Fig. 3 where the exhaustport 30 is uncovered to edect the escape of the compressed fluid from the cylinder. The air entrapped in the valve chest recess adjacent the shoulder 35 will be expelled during the forward translation of the valve through the ports V29 when it will Y flow into the cylinder and escape through the exhaust portV 30.

When the slide valve 25 is moved in its forwardly disposed position as in Fig. 3, the port 31 will be opened and thus communication between the source of compressed fluid and the forward portion of the cylinder will be established. Continuing the reciprocating event of the piston the compressed fluid now admitted intoy the portion o-f the cylinder adjacent the forward face of the piston will cause the retraction of theV piston and the closure of the exhaust port 30. When the stem of the piston closes the opening 33 in ,the valve chest cap and opens the annular recess 22 Vcompressed fluid will be admitted to the portion'of the cylinder adjacent the inner face of theV piston. The combined entrapped atmosphere and the compressed fluid in the inner portion of the cylinder bore during this event will flow through the ports 29 and against theshoulder. 35 ofthe slide valve u and will thus `cause the translationV of the V815 valve 25, the air entrapped in the valve chest recess adjacent the shoulder formed by the inner end of the cap 17 beingY expelledv to atmosphere through suitable vent ports in the usual manner. @The slidel valve in.` assuming this retracted position closes the port 31 thusV allocating the valvular members in j understood that the specific terminology is not intended to be restrictive or conning and it is further understood that various rear- V rangements of parts and modifications of structural detail may be resorted to without Vdeparting from the scopefor spirit'of the invention as herein claimed.

Iclaim:Y Y

1. 'In a fluid actuatedtool, a cylinder, a piston reciprocable therein, means on said piston to direct motive fluid to one end of saidcylnder, a slide valve toV control the admission of motive fluid to the other end 110 of said cylinder, differential pressure areas on said valve arranged to be exposed to the pressure of the live motive fluid, land another pressure area on said valve constantly ex-.... posed to the pressure in said one end of said cylinder.

2. In a fluid actuatedV tool, a cylinder, a valve chamber associated therewith, a piston reciprocable inl said cylinder and having a.. stem slidable in said valve chamber,a source "12o of motive fluid,` `passages communicating therewith and with the opposed ends of said cylinder, said stem being arranged to close said passages, a slide valveV in said valves; chamber arranged to close the passage to onef end of said cylinder to prevent the -flow of motivev fluid thereto, vand means responsive to pressure changes-in the other end of said cylinder to open-said valve. l F

3. In a fluid actuated tool, a cylinder, a 13a Lev-1,0622' I valve chamber associated therewith, a piston c reciprocable in said cylinder, a source of Inotive fluid, passages communicatinn,i therewith and with the opposed ends of said cylinder, means to control the admission of fluid to said cylinder including a valve in said valve chamber arranged to close the passage to one end of said cylinder and to be urged toward open position by the pressure of incoming motive fluid in said passage, and means responsive to pressures in the other end of said cyl inder to hold said valve in closed position during the maintenance of a pre-determined pressure in said other end.

l 4. In a fluid actuated tool, `a cylinder and a piston reciprocable therein, a passage for directing motive fluid to one end of the cylinder, a valve for controlling the flowl of fluid through said passage comprising a valve seat carried by the cylinder and a valve member carried by the piston, passages directing motive fluid to the other end of the cylinder, a second valve for controlling the flow of fluid through the last mentioned passage, the second valve being actua-ted by incoming motive fluid and controlled by the flow of motive fluid through the first mentioned valve.

5. In a fluid actuated tool, a cylinder, a valve chamber associated therewith, a piston reciprocable in said cylinder and having a stem slidable in said valve chamber, motive fluid passages leading to the opposite ends of said cylinder, said stem being arranged to close said passages, a. sleeve valve surrounding and spaced from said stem arranged to close the passage leading to one end of said cylinder, and urged toward open position by incoming motive fluid in said passage, and means to hold said sleeve valve in closed position during the maintenance of a pre-determined pressure in the other end of said cylinder.

In testimony whereof I hereunto affix my signature this 5th day of June, 1929. JOHN E. RENFER. 

